Is there a formal proof why this is the case?

Therefore the quantifier in your solution is redundant

Not really. Without it, the regex would match string like 'ab' as valid vowel.

Readability is important. Everything is clearly defined. Love it.

I still don't get it. Moving on

257ms

Perhaps more tests?

Is there only supposed to be 1 specific case that this should work?

From the spec: "Input - N - integer greater than 2 - number of chairs."

this solution is not passed under 3 people

In fact the "game" is useless. You should have realized that it only serves to present numbers on a chessboard
with a funny property when you want to calculate their sum.
Hint:

1. Take a sheet of paper and a pencil
2. Draw a chessboard 8 x 8
3. Put the numbers of the description on this chessboard
4. Examine the numbers
5. Try to calculate their sum lazily and intelligently
6. If you don't see their particularities go to 4

When you have understood the problem for 8x8, add a row and a column, fill them with numbers following the same rules as for a 8x8 chessboard. Now you are ready for a nxn chessboard.
There are no spaces, no token to move around, the result depends heavily on n.
Have a good day.

PS: it's useless to say that a description makes no sense:-)

this incomplete solution is pretty bad and shouldn't pass :\

Ahhh... JSON.parse is the part i was missing. Drat.

Well done!

Used your examples, thanks :)

I updated it with some examples. I'll try to be more active on this site again :) sorry!